New drug blocks transmission of malaria parasites

A new drug that blocks the transmission of malaria parasites by mosquitoes has been tested in humans for the first time by researchers at Radboud University Medical Center. Administration to healthy volunteers appears safe and the drug in the blood of volunteers prevents malaria parasite reproduction in the mosquito. A single injection of the drug could prevent transmission of parasites, and thus new malaria cases, during an entire malaria season.

Malaria is one of the most important infectious diseases of our time, with over 200 million cases and more than 600 thousand deaths each year. Young children in Africa, with poor access to health care, are particularly at risk of malaria. The parasites that cause this disease spread from one person to another via mosquitoes. Interrupting this highly efficient route of transmission is critical to reduce the global burden of malaria.

The new drug, an antibody called TB31F, was discovered and developed by a team of scientists in Nijmegen, the Netherlands.  Together with PATH's Malaria Vaccine Initiative, they conducted the first study with TB31F in humans. 25 healthy volunteers were administered TB31F, which proved safe and caused no important side effects. Next, researchers from the Malaria Unit of the Radboudumc determined the effect of TB31F, in the blood of the volunteers, on the transmission of parasites to mosquitoes.

Mechanism of action outside the body

In the Malaria Unit, researchers feed cultured malaria parasites to cultured mosquitoes, mimicking transmission from infected individuals to mosquitoes. Addition of the volunteers' blood containing TB31F completely blocked infection of the mosquitoes. Furthermore, the researchers estimate that one injection of TB31F may be able to prevent transmission of parasites from humans to mosquitoes for an entire malaria season in many parts of the world. When combined with other control measures, TB31F could become a valuable tool in the fight against malaria.

‘The remarkable thing is that this antibody actually works outside the human body’, explains clinical microbiologist Matthew McCall of the Radboudumc. ‘After being injected into a person, the antibody remains in the blood for several months, but it doesn't actually do anything there, not even if someone has malaria. Only when a mosquito bites and takes up blood containing both malaria parasites and the antibody, the antibody prevents the parasite from multiplying in the mosquito.  This way, the parasite cannot spread further and cannot cause more malaria cases.’